• ETRI Journal
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• 제37권6호
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• pp.1055-1064
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• 2015

We demonstrate a next-generation high-capacity mobile fronthaul based on radio over fiber (RoF) technology, which links between a digital unit and a radio unit supporting two frequency assignments and $2{\times}2$ multiple input, multiple output antennas. To confirm the technical feasibility of a mobile fronthaul, we experimentally investigate its down- and uplink end-to-end performances including the optical and radio frequency (RF) signal path. Frequency-dependent performance deviations, error vector magnitude variations, overall system performance variations caused by optical to electrical conversion, and intermediate frequency to RF conversions are examined. Experimental verifications on multiple LTE uplink signals are performed for the first time. We also demonstrate several commercial mobile Internet services, YouTube video streaming, and file transfers using off-the-shelf mobile devices, through a mobile fronthaul based on RoF.

• 한국학교보건학회지
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• 제4권1호
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• pp.116-125
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• 1991

The purposes of this study are to identify the degree of exercise intent and behavior and to determine factors influencing exercise and behavior in middle school students. The subjects for this study were 658 middle school students in Chonbuk area. The data were obtained by questionaire for the period from Nov. 1 to Dec. 20, 1990. The instrument used for the study were included 6 existing scales and 2 scales developed by the researcher for this study. They are: 1) The exercise intent scale to assess the exercise plan even when they had no longer physical education. 2) The current exercise behavior to measure of exercise frequency for 1 week. 3) The scale to measure the level of self -esteem. 4) The scale to measure the level of knowledge about exercise. 5) The scale to measure the level of the perceived ability to make commitment. 6) The scale to measure the level of the perceived benifit of exercise. 7) The scale to measure the level of the perceived athletic ability. 8) The scale to measure the level of the attitude toward physical education. The data were analyzed using frequency, percentage, one way ANOVA, Pearson Coeffecients Correlation and stepwise multiple regression. The following; results were obtained. 1. Exercise intent level was in the intermediate range(mean on five point scale of 3.66, with 1 = definitely no). 2. The current exercise behavior level was relatively low(mean=1.77, with l=less than once per week and 4 = 4 or more times per week). 3. Self -esteem levels were in the intermediate range(mean on five point scale of 2.96, a mean of 5.0 indicate highest level of self-esteem.) 4. The levels of perceived ability to make commitments were in the intermediate range(mean=3.05, with 5.0 as most able). 5. The levels of perceived exercise as benificial were relatively high(mean=3.72, with 5.0 as most benificial). 6. Knowledge levels about exercise were realatively high(mean=3.97, with 5.0 as most knowledgeable). 7. The levels of perceived athletic ability were in intermediate range(mean=3.01, with 5.0 as highest score). 8. The levels of attitudes toward physical education were in the intermediate range(mean=3.29, with 5.0 as most favorable). 9. Among the general characteristic variables, sex, interest sports activities were related to the difference of exercise intent levels. 10. Of the predictor variables analyzed, self - esteem, perceived benifit of exercise, perceived athletic ability, knowledge about exercise and attitude about physical education correlated significantly and positively with exercise intent. Correlations of predictors with current exercise behavior were similiar to exercise intent, exept knowledge about exercise. 11. The stepwise multiple regression analysis shows findings as follows: 1) The most important factor to explain the difference of exercise intent was current exercise behavior. 2) The most improtant factor to explain the difference of current exercise behavior was perceived athletic ability.

• 한국작물학회지
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• 제44권3호
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• pp.207-213
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• 1999

Thirty-eight glutinous rice varieties were classified into nine groups on the scatter diagram by the upper two principal components (56% contribution to the total information) based on eleven physicochemical characteristics including the viscograms and physical properties of cooked rice. The first principal component was the factor mainly associated with the viscogram characteristics of rice flour emulsion and the second was the factor chiefly related to the physical properties of cooked rice and water absorbability of rice grain. Indica glutinous rices were clearly distinguished from japonica ones by the first principal component score. Javanica glutinous rices were widely distributed on the intermediate zone between indica and japonica or on several japonica rice groups. Significant positive or negative correlations were found among water absorption rates of rice grain, physical properties of cooked rice, and viscogram characteristics of rice flour. Especially in japonica glutinous rices, the breakdown and setback viscosities of rice flour were closely associated with the alkali digestion value of milled rice and the stickiness of cooked rice. The frequency ratio of short glucose chains (A-chain) to intermediate glucose chains (B-chain), the ratio of B- chains to long glucose chains (C-chain) and the relative frequency of A- or B-chain fractions representing the amylopection structure of rice starch was closely associated with the breakdown and setback viscosities of rice flour.

• Preventive Nutrition and Food Science
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• 제7권2호
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• pp.207-214
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• 2002

Food preference of children may be determined by various lifestyle and environmental factors. This study evaluated the effect of rural or urban inhabitance, cooking methods, and frequency of exposure to vegetable dishes on the acceptance of vegetables by 452 fifth grade children. The subjects were students utilizing meal service in public elementary schools in Boryeoung-city, Chungcheong-nam-do (urban); Cheolwon-gun, Gangwondo (rural); or Pocheon-gun, Kyeonggi-do (suburban). A survey was used to determine the preference of students for 59 foods containing vegetables as a primary ingredient, and categorized by fat content (high, low, or intermediate). Children with working mothers and those living in urban areas tended to have less preference for vegetables than their counterparts in rural areas or with mothers who remained at home. Preference for vegetable foods was correlated with the frequency that vegetable foods were prepared by mothers. Vegetable dishes with a high fat content were preferred over those with low or intermediate fat content, except far soup. This study suggests that children who live in urban areas and whose mothers work outside of the home may be predisposed to nutritional deficiencies due to poor acceptance of vegetable foods, and that all children may be at risk for over-consumption of dietary fat, due to a preference for high fat foods.

• 한국세라믹학회지
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• 제45권11호
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• pp.725-733
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• 2008

In this study the preparation method of the spherical ADU droplets, intermediate compound of a HTGR nuclear fuel, was detailed-reviewed and then, the characteristics on an ageing and a washing steps among the wet process and the thermal treatment process on the died-ADU${\rightarrow}UO_3$ conversion with the high temperature furnaces were studied. The key parameters for spherical droplets forming are a precise control of feed rate and a suitable viscosity value selection of a broth solution. Also, a harmony of vibrating frequency and amplitude of a vibration dropping system are important factor. In our case, an uranium concentration is $0.5{\sim}0.7mol/l$, viscosity is $50{\sim}80$ centi-Poise, vibration frequency is about 100Hz. In thermal treatment for no crack spherical $UO_3$ particle, the heating rate in the calcination must be operated below $2^{\circ}C$/min, in air atmosphere.

• Journal of Advanced Marine Engineering and Technology
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• 제24권4호
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• pp.486-493
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• 2000

Flow mechanism around air flow sensor of electronic control engine, especially Karman vortex type, was investigated experimentally. The two-dimensional flow characteristics in the intermediate wake region behind a triangular vortex-generator respectively apex forward facing, apex backward facing and vertical flat plates following after apex forward facing(i.e vortex-flowmeter) were investigated at Reynolods number of $ReH=1.4\times10^4$; H is the width of a triangular vortex-generator. The vortex shedding frequency for wide Reynolds number from $7\times10^3$ to $2.1\times10^4$ was also surveyed. The velocity component was measured by X-type hot wire anemometer at 8H downstream from the bluff body. The coherent structure of the intermediate wake behind a bluff body was obtained by conditional phase average technique. As a result, it was verified that the vertical flat plates following after apex forward triangular vortex-generator make not only more linear relation between free stream velocity and vortex shedding frequency but also more periodic vortex in the vicinity of the center of wake.

• 소음진동
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• 제8권2호
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• pp.297-305
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• 1998

The finite element method is used for the study of the eigenvalue problems of partially fixed end beams with intermediate elastic supports. The elastic critical loads and natural frquencies of the beams are investigated by changing the numbers of elastic supports and their stiffness, and also by changing Kinney's fixity factor, $f_a$. The relationship between two eigenvalues is established by calculating the corresponding values of $(w/w_n)^2$ through changing $(P/P_{cr})$ values. The results of this study are as follows : (1) The elastic critical loads and natural frequencies of beams increase with increases in Kinney's fixity factor, $f_a$ and with the increased numbers of intermediate elastic supports. (2) The relationship between elastic critical loads and the natural frequencies of partially fixed end beams with intermediated elastic supports is $P/P_{cr} + (w/w_n)^2/ = 1$ without regard to Kinney's fixity factor, the stiffness of elastic supports, or the number of elastic supports.

• 설비공학논문집
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• 제10권2호
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• pp.173-179
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• 1998

An experimental study was conducted on the effect of compressor capacity control range of heat pump on the seasonal energy efficiency ratio with variation of the maximum and minimum compressor input frequencies. To obtain seasonal energy efficiency ratio, steady state test at the maximum, minimum and intermediate compressor speed and cyclic test at the minimum compressor speed should be conducted. Maximum input frequency was varied to 95Hz, 105Hz, and 115Hz, and the minimum input frequency was varied to 35Hz, 45Hz, and 55Hz. The seasonal energy efficiency ratio increased as the input frequency of the compressor decreased. The maximum input frequency had only slight effects on the SEER.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 E
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• pp.1867-1870
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• 1997

A Laser Doppler Vibrometer (LDV) based on the heterodyne method was developed using He-Ne laser as a light source. The heterodyne method was employed to eliminate the ambiguity in the direction of the motion. The frequency shifted object beam (40 MHz) by a Bragg cell was focused on the surface of the moving target and the Doppler shifted reflected beam was combined at the fast photodetector to produce frequency modulated signal centered at 40 MHz. The signal from the detector was amplified, filtered and downconverted to intermediate frequency centered at 5 MHz. The voltage output that was proportional to the velocity of the moving surface was obtained using PLL. This LDV can be used to measure the resonant frequency of the electric equipments such as circuit breakers and bushings, of which resonant frequencies are changed when they are damaged.

• Journal of Multimedia Information System
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• 제6권3호
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• pp.155-164
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• 2019

We intended to confirm that microwave attenuation by tree leaves is strongly linked to water content in leaves. We sampled natural broadleaves, including Japanese cinnamon, and investigated their effects on the microwave (3 to 20 GHz) frequency characteristics using a network analyzer. Experiments determined that microwave attenuation by foliage increases as a linear function of frequency per unit weight (gram). As the frequency increases, the spatial resolution increases, but the phase difference (imaginary component) increases. So we solved the dispersion of phase difference by sweeping the frequency and taking the intermediate value. Based on these experimental results, we developed a microwave scanner on 10Ghz to describe foliage moisture as a image and to enable assessments of leaf condition. Photosynthesis is the process whereby plants synthesize oxygen and sugars from carbon dioxide and water, thereby converting light energy into chemical energy. Since water is a major parameter of photosynthesis, the quantity of water accumulated inside a leaf reflects leaf health. The equipment described here and related microwave technologies will help assess the capacity of leaves to absorb atmospheric carbon dioxide.